Trying to figure out what the part is

My friend was driving over a speed bump and heard a thunk at the rear of her vehicle, she stopped and found something made of rubber with a metal plate on it that has a Chrysler symbol on it and says 287 Front Green 24861 25 1B.



I have tried to search the internet but have been unable to determine what it is. She is concerned that it may affect safety of the vehicle

BTW, here is a picture of the part.